1. Field of the Invention
The present invention relates to a push switch, such as a pushbutton switch used in the operation portion of an electronic apparatus, a portable device, a vehicle-mounted switch, a remote controller etc., or a membrane switch used in an electronic apparatus, for example, as a thin switch input device.
More specifically, the present invention relates to a method for forming, on a pushbutton switch, an indicator portion in which color design images such as letters, patterns, and designs are indicated, and to a pushbutton switch having the indicator portion.
Also, the present invention relates to a method for forming, on a membrane switch, an indicator portion in which color design images such as letters, patterns, and designs are indicated, and a membrane switch having the indicator portion.
2. Description of the Related Art
Pushbutton switches used in electronic apparatuses such as portable telephones have an indicator layer for the indication of color design images such as letters, numerals, figures, symbols, and design patterns. Such an indicator layer is formed by printing shapes corresponding to letters, symbols, or the like on a key top mainly formed of a resin, by screen printing, pad printing, or the like.
However, with the recent trend toward miniaturization and an increase in the functions of electronic apparatuses, key tops of pushbutton switches are also becoming increasingly smaller in size. Thus, there is a need to enable indication of as many letters or numerals as possible, or complex figures, symbols, design patterns, etc. formed using multiple colors, on a small key top having a limited space. Consequently, with the conventional methods such as screen printing or pad printing, it has become increasingly difficult to form an indicator layer which is capable of high resolution, the resolution being a measure of the meticulousness of a drawing or the smoothness of an image, and on which fine, sharp designs are rendered. Further, the screen printing and the pad printing require the use of a printing plate for each color, so that the number of printing steps increases as the number of colors for printing increases, thus necessitating sophisticated printing techniques that enable a fine positional adjustment, or measures for preventing the intrusion of contaminants. Further, when changing the design of a pushbutton switch, it is necessary to prepare new printing plates. Thus, the printing plates are prepared in accordance with colors required for each product, so that a great deal of time, labor, and costs is involved in storing and maintaining the printing plates. Due to the reasons described above, conventional methods based on printing, for example screen printing and pad printing, have proved inadequate to quickly respond to the diversity of designs and shorter life cycles, making it impossible to meet such demands as the simplification of the production steps, reduction in cost, and higher resolution.
In contrast, as an alternative method for preparing an indicator layer on a pushbutton switch to the conventional printing methods, there is a method of bonding onto a key top a photographic sheet formed on a resin sheet by graphic photo-printing using a printer. A similar technique is described in JP 2000-231849 A. However, with the above method, it is necessary to perform a post-processing of cutting the photographic sheets along the outer peripheral configurations of individual key tops using a carbon dioxide laser or a punching edge. In addition, because a rather thick photographic sheet is cut, burrs are easily produced on the cut surfaces. Further, the photographic sheet is integrated with the key top, making the above method unsuitable for dealing with the demand for reduced thickness.
Membrane switches are used as thin switch input devices in, for example, electronic apparatuses. An example of conventional membrane switches is shown in FIGS. 17 and 18. Such a conventional membrane switch, denoted 100, commonly has a construction as shown in FIGS. 17 and 18. That is, the membrane switch is generally composed of a front-side film, or sheet material 101 that is exposed to the outward appearance of a not-shown electronic apparatus, a back-side film, or sheet material 102 received within the inner portion of the electronic apparatus, and a spacer 103 arranged between the two film materials. Formed on the two sheet materials 101 and 102 are contact electrodes 101a and 102a, respectively. When pressed from above, the contact electrode 101a of the front-side sheet material 101 is brought into conducting contact with the contact electrode 102a of the back-side sheet material 102 by way of a through hole 103a formed in the spacer 103. Establishing such conducting contact makes it possible to attain a predetermined switch function of the electronic apparatus. Advantages of the membrane switch 100 described above reside in the simplicity of its construction and its small thickness. As such, the switch is employed in various apparatuses as a switch input device of an electrical apparatus for which there is a particularly strong demand for miniaturization.
In such a membrane switch 100, in general, letters, numerals, symbols, figures etc. are colors for indication or a colored exterior film 104 is bonded onto a portion thereof which is exposed to the outward appearance of the electronic apparatus. Such an exterior film 104 is typically obtained by screen-printing a coating material onto a resin film. However, with screen printing, it is necessary to prepare a printing plate for each color, which places a large burden in terms of both labor and cost. Further, when changing the design, it is necessary to prepare all new printing plates from scratch, which leads to a further increase in labor and cost. To overcome the above problem, there is proposed a method for forming the exterior film 104 which includes: preparing a design by a personal computer; printing the design on a base sheet (not shown) such as paper or a PET film using a commercially available color printer to thereby prepare the external film 104; and stacking the exterior film 104 on the front-side film material 101 using an adhesive tape or the like (for a similar technique, see Japanese Utility Model Application Laid-open No. Hei 5-90762).
However, with the above-described method, it is also necessary to perform a step of cutting the exterior film 104 along the outer peripheral configurations of individual membrane switches using a carbon dioxide laser or a punching edge. In addition, burrs are easily generated resulting from the cutting step. Further, with the above-described method, it is commonly necessary to provide a protection sheet for protecting the printing surface subjected to printing using a color printer, which leads to a considerable increase in the overall thickness inclusive of the thickness of the base sheet. If the resulting structure is integrated as a part of the membrane switch, the flexibility of a portion subjected to pressing operation with, for example fingers is impaired, resulting in such problems that the operational feel as a membrane switch is degraded, on/off operation of the switch is not properly effected by the pressing operation, and the like. Therefore, the above-described method is not suitable for application to membrane switches whose structural advantages reside in their small thicknesses. On the other hand, to avoid the problem described above, the printing surface subjected to printing by a color printer may be bonded onto a portion that is exposed to the outward appearance of the electronic apparatus. With this arrangement, however, the color design image is viewed from the back (from the side opposite to the printing surface), so that the image appears distorted. Thus, it is often difficult to view the image with good reproducibility while maintaining high resolution.
The present invention enables forming an indicator portion having an excellent design image, on a push switch such as a pushbutton switch or a membrane switch.
That is, an object of the present invention is to inexpensively provide an indicator portion for pushbutton switch which enables indication of a large number of letters, symbols, or complex, fine picture patterns, design etc. with clarity and high resolution, allows a reduction in the number of manufacturing steps without requiring sophisticated printing techniques etc., and results in excellent design property and image quality.
Another object of the present invention is to provide an indication portion for a membrane switch, in which letters, symbols, or patterns etc. serving as input elements exposed to the outward appearance of an apparatus has high resolution while exhibiting excellent design property and image quality, and a membrane switch having the indicator portion.
To achieve the above objects, according to the present invention, there is provided an indicator portion forming method for a push switch, in which an indicator portion indicating a color design image such as a letter, a pattern, or a design is formed on the push switch, the method including: forming a colorant layer by printing a color design image on a base sheet by a printer; transferring the colorant layer to a transfer resin through an adhesive, the transfer resin constituting a surface of the push switch; and forming an indicator layer on the transfer resin by peeling off the base sheet and using the colorant layer as the indicator layer.
According to the indicator portion forming method for a push switch, the method performs the steps of: forming a colorant layer by printing a color design image on a base sheet by a printer; transferring the colorant layer to a transfer resin through an adhesive, the transfer resin constituting a surface of the push switch; and forming an indicator layer on the transfer resin by peeling off the base sheet and using the colorant layer as the indicator layer. As a result, an inexpensive, high-quality indicator portion can be obtained which allows a large number of letters, numerals, figures, symbols etc., or patterns of complex configurations with multiple colors to be indicated with sharp clarity on a small area of the push switch surface and which can be produced in a stable manner without relying on the skill of an operator.
Further, according to the present invention, there is provided an indicator portion forming method for a push switch, in which the push switch is a pushbutton switch having a key top made of resin and the transfer resin is a key top main body of the pushbutton switch. According to the indicator portion forming method for a push switch described above, the base sheet is peeled off after the colorant layer is transferred to the transfer resin. As a result, a pushbutton-switch key top having a thin indicator layer can be obtained. Further, since the method does not involve cutting or punching out the base sheet, the pushbutton-switch key top obtained is of high quality with little generation of burrs. Thus, a pushbutton switch having such a key top is obtained.
Further, according to the present invention, the push switch is a membrane switch including: an operation sheet which is provided with an indicator layer indicating a color design image such as a letter, a pattern, or a design and on which a depressing operation is performed; and a switch portion having contact electrodes provided in opposed positions, the switch portion executing a predetermined switch function when the contact electrodes, that are insulated from each other, are brought into electrical connection by the depressing operation on the operation sheet, and the transfer resin is a translucent film constituting a part of the operation sheet.
When the push switch is formed as a membrane switch, an indicator layer having excellent resolution representing the meticulousness of a drawing or the smoothness of an image can be formed on the membrane switch stably and inexpensively without using complex printing techniques. As a result, a high-quality membrane switch can be obtained. In particular, since the base sheet is peeled off in the course of forming the operation sheet of the membrane switch, the operation sheet can be reduced in thickness, thereby making it possible to obtain a membrane switch with a good operating feel and an excellent operational accuracy. Further, the colorant layer is transferred, so that the resulting membrane switch has an indicator layer of high quality, which can be formed without requiring cutting or punching out the base sheet after the transfer process and in which few burrs are produced.
Further, according to the present invention, there is provided an indicator portion forming method for a push switch, in which the transfer resin is formed of a transparent or semi-transparent resin and the colorant layer is transferred to a back surface of the transfer resin.
According to the indicator portion forming method for a push switch, the transfer resin is formed of a transparent or semi-transparent resin and the colorant layer is transferred to the back surface of the transfer resin. As a result, even when the colorant layer is transferred, a color design image outputted by a printer can be viewed from the front side (the printing surface side), thereby making it possible to form an image such as a letter, a symbol, a pattern etc. having high resolution and high appearance quality. Where the image is viewed from the side opposite to the printing surface side, ink smears onto the base sheet or a receiving layer and the like formed on the base sheet, so that there are cases where a surface with ink smeared thereon is viewed. Therefore, it is considered that viewing an image from the printing surface side results, in many cases, in a resolution superior to that obtained when the image is viewed from the side opposite to the printing surface.
Further, according to the present invention, there is provided an indicator portion forming method for a push switch, in which the base sheet has an image bearing layer and the colorant layer is formed by printing a color design image on the image bearing layer by using a printer.
According to the indicator portion forming method for a push switch, the base sheet has an image bearing layer and the colorant layer is formed by printing a color design image on the image bearing layer by using, a printer, thereby making it possible to reproduce an image having excellent resolution with excellent adherence and absorption of a colorant such as ink or toner. Further, in addition to having an indicator layer of excellent water resistance and weatherability in which the colorant is protected with the image bearing layer, because the colorant layer can be transferred onto the transfer resin side with accuracy, the push button obtained has high appearance quality and is excellent in terms of resolution and image quality. In particular, if the image bearing layer is formed of a porous material having a binding phase composed of inorganic particles that are bound by a binder resin, a push switch is obtained which is excellent in terms of transfer property with little generation of burrs even when removing the base sheet, as well as in terms of ink absorption, storage stability of the indicator layer, and appearance quality of the obtained image. Further, if the image bearing layer is provided with a large number of longitudinal pores opening in a direction normal to the base sheet surface, the image bearing layer is readily exfoliated upon the transfer and is therefore excellent in terms of transferability. In particular, when an ink jet printer is used, ink absorption is effected instantaneously due to the strong ink absorption force afforded by the ink jet printer, making it possible to obtain a push switch allowing high appearance quality of the obtained image with no running of ink.
Further, according to the present invention, there is provided an indicator portion forming method for a push switch, the method including forming an auxiliary coloring layer for adding such colorations as metallic colors like gold, silver etc., or a white color.
According to the indicator portion forming method for a push switch, the method includes performing the step of forming the auxiliary coloring layer for adding such colorations as metallic colors like gold, silver etc., or a white color. Therefore, an image having colorations such as metallic colors like gold, silver etc, or white, pearl etc., which are difficult to reproduce with a color printer that typically uses CMYK ink, can be easily formed, whereby an indicator portion with good color reproducibility which is excellent in terms of image quality and design can be obtained. In particular, it is possible to perform the step of forming an auxiliary coloring layer, which serves to add such colorations as metallic colors like gold, silver etc., or a white color, on a transfer resin or on a colorant layer before or after the colorant layer is transferred onto the transfer resin.
Further, according to the present invention, there is provided an indicator portion forming method for a push switch, in which the adhesive is a transparent or semi-transparent hot-melt adhesive, and the transfer of the colorant layer is effected by thermal transfer.
According to the indicator portion forming method for a push switch, the transfer of the colorant layer is effected by thermal transfer using a transparent or semi-transparent hot-melt adhesive, whereby the curing time of the adhesive is shortened and the transfer process is completed instantaneously to achieve good operability and high productivity, and further high operational efficiency is attained since there is no need to additionally provide a step for curing the adhesive. Additionally, the method ensures high quality, little generation of burrs etc., and excellent yield since it allows a desired portion to be transferred onto the transfer resin with accuracy. Further, a push switch having the indicator portion that is obtained by the above-described method is formed by using a hot-melt adhesive, so that it is excellent in terms of humidity resistance and storage stability without causing any change in its strength etc. over time. Further, the adhesive used is a transparent or semi-transparent adhesive, so that an illuminated push switch can be obtained which can sufficiently transmit light with no loss of clarity of an image formed on the indicator layer.
Further, according to the present invention, there is provided an indicator portion forming method for a push switch, the method including printing a color design image by using a printer employing an ink jet printing system.
According to the indicator portion forming method for a push switch, an ink jet printer is used as the printer, whereby full color representation and high speed printing are facilitated, thus allowing instantaneous imaging of color design data. Further, there can be obtained an indicator portion realizing a near-photograph image quality and excellent resolution. Further, ink for the ink jet printer is transferred while remaining infiltrated in the porous material, whereby a push switch having an indicator layer that is excellent in terms of weatherability and color developability can be obtained.
Further, according to the present invention, there is provided a push switch having an indicator portion indicating a color design image such as a letter, a pattern, a design etc., characterized by including an indicator layer on a surface of the push switch, the indicator layer being obtained by printing the color design image through an adhesive layer by using a printer.
According to the, push switch, the indicator layer, which is obtained by printing a color design image through an adhesive layer by using a printer, is provided on a surface of the push switch. Therefore, a push switch is obtained which allows a large number of letters, numerals, symbols etc, or patterns of complex configurations with multiple colors to be indicated with sharp clarity and at high resolution on a small area of the push switch surface.
Further, according to the present invention, the push switch may be used as a pushbutton switch having a key top made of resin. Also, according to the present invention, the push switch may be used as a membrane switch including: an operation sheet which is provided with an indicator layer for indicating a color design image such as a letter, a pattern, or a design and on which a depressing operation is performed; and a switch portion having contact electrodes provided in opposed positions, the switch portion executing a predetermined switch function when the contact electrodes that are insulated from each other are brought into conduction by the depressing operation on the operation sheet.
If the push switch is used as a pushbutton switch or a membrane switch, the pushbutton switch or the membrane switch thus obtained has an indicator portion capable of indicating a large number of letters, numerals, symbols etc., or patterns of complex configurations with multiple colors on a surface of the pushbutton switch or the membrane switch. Further, the indication portion can be formed to have a small thickness, so that when it is applied to a membrane switch, there is obtained a membrane switch that provides good operating feel with respect to a depressing operation with no loss of the flexibility of the operation sheet that is subjected to displacement upon the depressing operation.
Further, according to the present invention, there is provided a push switch to be used as a membrane switch in which the operation sheet constitutes a part of the switch portion and contact electrodes are formed on the operation sheet.
According to the membrane switch, the operation sheet constitutes a part of the switch portion, so that there is no need to join the operation sheet having an indicator layer onto the switch portion executing the switch function, and the resulting absence of a joint portion allows a corresponding reduction in layer thickness. Further, the contact electrodes are formed on the operation sheet, so that a flexible film having the contact electrodes provided thereon need not be provided separately from the operation sheet. Therefore, a reduction in layer thickness is achieved as compared with the case where the operation sheet is laminated on the flexible film, whereby a membrane switch is obtained which provides an excellent operating feel with respect to a depressing operation with hardly any no loss of the flexibility of the operation sheet that is subjected to displacement upon the depressing operation.
Further, if the front surface of the push switch is formed of a translucent resin and the indicator layer is formed on the back surface of the translucent resin, a color design image printed by a printer can be viewed from the front side (the printing surface side), thereby making it possible to form an image such as a letter, a symbol, a pattern etc. having high resolution and high appearance quality. Further, if the indicator layer is obtained by printing it on a base sheet having a porous image bearing layer and impregnating ink into the image bearing layer, an image of excellent resolution can be reproduced which is excellent in terms of ink absorption and formed of dots that are closer to regular circles. Further, in addition to having an indicator layer of excellent water resistance and weatherability in which the colorant constituting ink is protected with the image bearing layer, because the colorant layer can be transferred onto the transfer resin side with accuracy, the push button obtained has high appearance quality and is excellent in terms of resolution and image quality. In particular, if the image bearing layer is formed of a porous material having a binding phase composed of inorganic fine particles that are bound by a binder resin, a push switch is obtained which is excellent in terms of transfer property with little generation of burrs even when removing the base sheet, as well as in terms of ink absorption, storage stability of the indicator layer, and appearance quality of the obtained image. Further, if the image bearing layer is provided with a large number of longitudinal pores opening in a direction normal to the base sheet surface, the image bearing layer is readily exfoliated upon the transfer and is therefore excellent in terms of transferability.
Further, according to the present invention, the push switch may further have an auxiliary coloring layer for adding such colorations as metallic colors like gold, silver etc., or a white color. If the auxiliary coloring layer for adding such colorations as metallic colors like gold, silver etc., or a white color is provided, an image having colorations such as metallic colors like gold or silver, white, pearl etc., which are difficult to reproduce with a color printer that typically uses CMYK ink, can be indicated with sharp clarity, whereby the obtained pushbutton switch has good color reproducibility and is excellent in terms of image quality and design.
Further, if the adhesive layer is formed of a hot-melt adhesive, there can be obtained a push switch realizing near-photograph image quality and excellent resolution.
Further, according to the present invention, there is provided a so-called illuminated push switch in which the respective layers constituting the push switch are translucent so that light exiting from an inner light source can be transmitted therethrough to the exterior for illumination. According to the push switch, the light from the inner light source is transmitted through the push switch to the exterior for illumination, thereby realizing improved decorative property and improved visibility at night or in a dark place.
The foregoing description of the present invention should not be construed restrictively. The objects, advantages, features, and uses of the invention will become more apparent from the following description given with reference to the accompanying drawings. Further, it is to be understood that various modifications made without departing from the gist of this invention fall within the scope of the invention.